The invention relates to compounds having luminescent properties, and to methods of synthesizing and using such compounds. The invention more particularly relates to compounds having photoluminescent and/or electroluminescent properties, and to synthesis and uses of same.
A variety of luminescent compounds are known in the art. Green and red luminescent compounds are not uncommon, but blue luminescent metal ions and molecules are rare and generally expensive.
Two types of blue luminescent inorganic coordination compounds are known in which a heterocyclic chromophore includes a metal center coordinated by nitrogen and oxygen atoms of organic ligands. One type is based on 8-hydroxyquinoline and derivatives thereof, and the other is based on azomethine and derivatives thereof. Both the 8-hydroxyquinoline- and azomethine-based systems usually require several steps of synthesis and modification in order to achieve blue luminescence. The usefulness of these two systems in practical electroluminescence applications is limited, and blue luminescent materials with improved properties are desirable.
Production of devices based on electroluminescent display, and in particular on flat panel display, is a rapidly growing, billion dollar industry. Blue luminescent materials, as one of the key color components for electroluminescence display devices, are among the most sought-after materials by industry around the world.
It is an object of the present invention to provide blue luminescent compounds with improved properties. Another object of the invention is to provide improved luminescent products including such a compound. As used herein, the term xe2x80x9ccompoundxe2x80x9d includes coordination complexes, sometimes referred to simply as xe2x80x9ccomplexesxe2x80x9d. The term xe2x80x9caliphaticxe2x80x9d includes alkyl, alkenyl and alkynyl, and straight and branched chain.
The invention provides compounds having the following formulas:
(i) [AlR2(azain)]n,
(ii) [AlR2(dpa)]n,
(iii) [Al4R6O2(dpa)2],
(iv) Al(PFPA)3, and
(v) derivatives of (i), (ii), (iii) and (iv),
where R is aliphatic, aryl or alkoxyl, azain is deprotonated 7-azaindole, dpa is deprotonated di-2-pyridyl amine, and PFPA is deprotonated pentafluorophenyl-2-pyridylamine. The compounds are photoluminescent and, in at least some embodiments of the invention, they are electroluminescent; they produce intense blue light.
The invention also provides compounds having the following formulas:
(i) Al2R2(azain)4,
(ii) Al2(R)(azain)2(ORxe2x80x2)3,
(iii) Al3(R)(azain)4(ORxe2x80x2)2(O),
(iv) Al3R3(azain)4(O), and
(v) derivatives of (i), (ii), (iii) and (iv)
where R and Rxe2x80x2 are aliphatic, aryl or alkoxyl groups, azain is deprotonated 7-azaindole, and dpa is deprotonated di-2-pyridyl amine. The compounds are photoluminescent and, in at least some embodiments of the invention, they are electroluminescent; they produce intense blue light.
The invention further provides corresponding compounds wherein aluminum is replaced by boron. Such corresponding compounds include compounds having the following formulas:
(i) B(dpa)X2,
(ii) [BR2(azain)]n 
(iii) B2R2(azain)2(O),
(iv) BR3(azainH), and
(v) derivatives of (i), (ii), (iii) and (iv),
where azain is deprotonated 7-azaindole, dpa is deprotonated di-2-pyridyl amine, X is halide or alkoxyl, and R is aliphatic, aryl or alkoxyl.
Such corresponding compounds also include compounds having the following formulas:
(i) [BR(dpa)2]n 
(ii) [BR2(dpa)]n, and
(iii) derivatives of (i) and (ii)
where dpa is deprotonated di-2-pyridyl amine, and R and Rxe2x80x2 are aliphatic, aryl or alkoxy groups.
The boron compounds of the invention are photoluminescent and, in at least some embodiments of the invention, they are electroluminescent; they produce intense blue light.
The term xe2x80x9cderivativesxe2x80x9d includes compounds where derivatives of 7-azaindole (e.g., phenyl-7-azaindole, methyl-7-azaindole, disubstituted compounds, and the like) and derivatives of di-2-pyridyl amine are subsituents of the compounds, as discussed below. In certain embodiments of the invention, these may provide advantageous physical or chemical properties.
The invention provides a method of synthesizing a compound of the invention including the step:
n AlR3+n dpa (or azainH)xe2x86x92[AlR2(dpa)]nor [AlR2(azain)]n+n RH,
where (n=1 or 2).
The invention further provides a method of synthesizing a compound of the invention including the step:
2n AlR3+n H2O+n dpa(or azainH)xe2x86x92[Al2R3(O)(dpa)]n or [Al2R3(O)(azain)]n+3n RH, and
AlR3+3PFPA-Hxe2x86x92Al(PFPA)3+3RH.
The invention also provides a method of synthesizing a compound of the invention including a step selected from the following group:
2 AlR3+4 azainHxe2x86x92Al2R2(azain)4+4RH,
2 AlR3+2 azainH+3Rxe2x80x2OHxe2x86x92Al2(R)(azain)2(ORxe2x80x2)3+5 RH,
3 AlR3+4 azainH+H2O+2 Rxe2x80x2OHxe2x86x92Al3(R)(azain)4(ORxe2x80x2)2(O)+8 RH, and
3AlR3 +4 azainH+H2Oxe2x86x92Al3(R)3(azain)4(O)+6RH,
where R and Rxe2x80x2 are aliphatic, aryl or alkoxy groups.
The invention further provides a method of synthesizing a compound of the invention including a step selected from the following group:
n BR3+n azainHxe2x86x92[BR2(azain)]n+n RH (n=1, 2),
2 BR3+2 azainH+H2Oxe2x86x92B2R2(azain)2(O)+4 RH, and
BR3+azainHxe2x86x92BR3(azainH)
where R and Rxe2x80x2 are aliphatic, aryl or alkoxy groups.
The invention also provides a method of synthesizing a compound of the invention including a step selected from the following group:
n BR3+2n dpaxe2x86x92[BR(dpa)2]n+2n RH and
n BR3+n dpaxe2x86x92[BR2(dpa)]n+n RH,
where R and Rxe2x80x2 are aliphatic, aryl or alkoxy groups.
The invention provides a method of producing photoluminescence comprising the steps of: providing a photoluminescent compound of the invention having a formula as set out above (or a derivative thereof); and irradiating said photoluminescent compound with radiation of a wavelength suitable for exciting the compound to photoluminesce.
The invention provides a method of producing electroluminescence comprising the steps of: providing an electroluminescent compound of the invention having a formula as set out above (or a derivative thereof); and applying a voltage across said electroluminescent compound.
The invention further provides use of a compound of the invention as a component of a photoluminescent product or an electroluminescent product. For example, a luminescent compound could be used as a luminescent probe, or as a thin film in an electroluminescent display, such as a flat panel display device.
The invention still further provides an electroluminescent device for use with an applied voltage, comprising: a first electrode, an emitter (i.e., phosphor) which is an electroluminescent compound of the invention, and a second, transparent electrode, wherein a voltage is applied between the two electrodes to produce an electric field across the emitter. The emitter consequently electroluminesces. In some embodiments of the invention, the device includes one or more dielectric layers interposed between the emitter and one or more of the electrodes. For example, spacing of a preferred embodiment of the device is: first electrode, first dielectric layer, emitter, second dielectric layer, and second, transparent electrode.
In addition, the invention provides methods of applying compounds of the invention to a surface. These include chemical vapor deposition, spin coating and dip coating. The compounds may be applied alone or with a carrier. In some embodiments of the invention, they are applied in a composition including an organic polymer. Such compositions are also encompassed by the invention.